Effects of indomethacin on sunburn and suntan reactions in hairless descendants of Mexican hairless dogs.
The inhibitory effects of topical indomethacin (IM)-treatment on sunburn and suntan reactions after ultraviolet (UV)-irradiation were investigated in the dorsal skin of hairless descendants of Mexican hairless dogs. Skin color, plasma prostaglandin E2 (PGE2) and histological features were examined. At 1 day after UV-irradiation, the IM-untreated sites showed prominent erythema, while the IM-treated sites exhibited few visible erythematous reactions. From 4 days after UV-irradiation, both the IM-treated and -untreated sites began to develop skin pigmentation. Assessment of skin color changes, using a colorimeter, reflected precisely the color changes in visual sunburn and suntan reactions. Plasma PGE2 concentration began to increase from 2 hours after UV-irradiation, reached the maximal values at 24 hours and recovered at 96 hours after UV-irradiation. Histologically, at 1 day after UV-irradiation, the IM-untreated sites showed remarkable epidermal degeneration (thickening and sunburn cells) and moderate alteration in the dermis. On the other hand, the IM-treated sites showed only minor histological changes. At 4 days after UV-irradiation, deposition of melanin granules was found in both the IM-treated and -untreated sites. At 7 days after UV-irradiation, pigmentation became more prominent in the stratum basale. These results revealed that UV-induced erythematous reactions of hairless dogs were closely related to the action of PGE2. Visually and histologically, topical IM-treatment had apparent inhibitory effects on erythematous reactions, while this agent showed no protective effects on epidermal pigmentation after UV-irradiation.
Kimura
T
T
Research Center, Nihon Nosan Kogyo Co., Ltd., Ibaraki, Japan.
Doi
K
K
D000287:Administration, Topical; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000494:pharmacology*; D015232:Dinoprostone / Q000097:blood; D004285:Dogs; D005260:Female; D007213:Indomethacin / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D012867:Skin / Q000187:drug effects* / Q000473:pathology / Q000528:radiation effects*; D012880:Skin Pigmentation / Q000187:drug effects* / Q000528:radiation effects*; D013471:Sunburn / Q000473:pathology* / Q000662:veterinary*; D014466:Ultraviolet Rays
D000894:Anti-Inflammatory Agents, Non-Steroidal; D015232:Dinoprostone; D007213:Indomethacin